Charge/discharge control method

Abstract

A secondary battery charging method includes the step of determining whether to perform one of a first charging control method of performing constant current charging and constant voltage charging and a second charging control method of performing only the constant current charging according to information stored in a plurality of secondary batteries including a compound oxide particle with an olivine crystal structure. The first charging control method includes the steps of performing the constant current charging of the secondary batteries, performing the constant voltage charging, determining whether voltage variation amounts of the plurality of secondary batteries are a value equal to or greater than a first set value, and storing information and firstly terminating the charging. The second charging control method includes the steps of starting the constant current charging of the plurality of secondary batteries connected to each other in series, and secondly terminating the constant current charging.

What is claimed is: 
     
       1. A secondary battery charging method comprising the step of:
 determining whether to perform one of a first charging control method of performing constant current charging and constant voltage charging and a second charging control method of performing only the constant current charging according to information stored in a plurality of secondary batteries which includes a compound oxide particle with an olivine crystal structure as a positive electrode active material and are connected to each other in series, 
 wherein the first charging control method includes the steps of 
 performing the constant current charging of the secondary batteries until the voltages of the plurality of secondary batteries connected to each other in series become a predetermined battery voltage, 
 performing the constant voltage charging after the voltages of the secondary batteries become the predetermined battery voltage, 
 determining whether voltage variation amounts of the plurality of secondary batteries are a value equal to or greater than a first set value within a first predetermined time by measuring the voltage variation amounts of the plurality of secondary batteries after the constant voltage charging starts, and 
 storing information used to select the second charging control method in the secondary battery and firstly terminating the charging when it is determined that the voltage variation amount of at least one of the plurality of secondary batteries is the value equal to or greater than the first set value within the first predetermined time in the step of determining whether the voltage variation amounts of the plurality of secondary batteries are the value equal to or greater than the first set value within the first predetermined time, and 
 wherein the second charging control method includes the steps of 
 starting the constant current charging of the plurality of secondary batteries connected to each other in series, and 
 secondly terminating the constant current charging when the voltage variation amount of at least one of the plurality of secondary batteries is a value equal to or greater than a second set value within a second set time. 
 
     
     
       2. The secondary battery charging method according to  claim 1 , wherein in the step of determining whether the voltage variation amounts of the plurality of secondary batteries are the value equal to or greater than the first set value within the first predetermined time in the first charging control method, it is determined whether the voltage variation amount of at least one of the plurality of secondary batteries is the value equal to or greater than the first set value within the first predetermined time. 
     
     
       3. The secondary battery charging method according to  claim 1 , wherein in the step of determining whether the voltage variation amounts of the plurality of secondary batteries is the value equal to or greater than the first set value within the first predetermined time in the first charging control method, it is determined whether an average value of the voltage variation amounts of the plurality of secondary batteries is the value equal to or greater than the first set value within the first predetermined time. 
     
     
       4. The secondary battery charging method according to any one of  claims 1  to  3 , wherein the second set time does not include a start time of the constant current charging in the second charging control method. 
     
     
       5. The secondary battery charging method according to  claim 1 , wherein the first charging control method further includes the steps of
 determining whether the voltage variation amounts of the secondary batteries are a value equal to or greater than the first set value within a second predetermined time longer than the first predetermined time by measuring the voltage variation amounts of the plurality of secondary batteries after the constant voltage charging starts, and 
 storing information used to select the second charging control method in the secondary battery and thirdly terminating the charging when it is determined that the voltage variation amount of at least one of the plurality of secondary batteries is the value equal to or greater than the first set value within the second predetermined time in the step of determining whether the voltage variation amounts of the plurality of secondary batteries are the value equal to or greater than the first set value within the first predetermined time.